(a) Field of the Invention
The present description relates to a thin film transistor (TFT) array panel for a liquid crystal display (LCD) or an organic light emitting display (OLED) and a manufacturing method for the same.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. An LCD includes a liquid crystal (LC) layer interposed between two panels provided with field-generating electrodes. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer that determines orientations of LC molecules in the LC layer to adjust the polarization of incident light.
An LCD including two panels provided with field-generating electrodes respectively, wherein one panel has a plurality of pixel electrodes in a matrix and the other has a common electrode covering the entire surface of the panel, dominates the LCD market.
The LCD displays images by applying a different voltage to each pixel electrode. For this purpose, thin film transistors (TFTs), having three terminals to switch voltages applied to the pixel electrodes, are connected to the pixel electrodes, and gate lines to transmit signals for controlling the thin film transistors and data lines to transmit voltages applied to the pixel electrodes are formed on a thin film transistor array panel.
A TFT is a switching element for transmitting the image signals from the data wire to the pixel electrode in response to the scanning signals from the gate wire.
The TFT is applied to an active matrix organic light emitting display as a switching element for controlling respective light emitting elements.
Meanwhile, chromium (Cr) is conventionally the predominant material used for the gate line and the data line of a TFT array panel. However, Cr includes the drawbacks of high stress and resistivity.
Considering the trend of increasing LCD size, a material having low resistivity is urgently required since the lengths of the gate and data lines increase along with the LCD size. Accordingly, Cr is not appropriate for use in a large size LCD.
Aluminum (Al) is a well known material as a substitution for Cr due to its low resistivity. However, Al also has drawbacks including hillock growth that may be induced by high temperature, Al may be diffused into a semiconductor when Al contacts the semiconductor, and, since Al has poor contact characteristics with pixel electrode materials, such as indium tin oxide (ITO), a poor contact between a drain electrode of Al and a pixel electrode of ITO may occur.